Google Maps (for a time named Google Local) is a basic web mapping service application and technology provided by Google, free (for non-commercial use), that powers many map-based services, including the Google Maps website, Google Ride Finder, Google Transit,[1] and maps embedded on third-party websites via the Google Maps API.[2] It offers street maps, a route planner for traveling by foot, car, or public transport and an urban business locator for numerous countries around the world. According to one of its creators (Lars Rasmussen), Google Maps is "a way of organizing the world's information geographically".[3]

Satellite view

Google Maps provides high-resolution satellite images for most urban areas in the United States (including Hawaii, Alaska, Puerto Rico, and the U.S. Virgin Islands), Canada, and the United Kingdom, as well as parts of Australia and many other countries. The high-resolution imagery has been used by Google Maps to cover all of Egypt's Nile Valley, Sahara desert and Sinai. Google Maps also covers many cities in the English speaking areas. However, Google Maps is not solely an English maps service, since its service is intended to cover the world. The highest-resolution images are in some Japanese cities, such as Tokyo.[citation needed]

Various governments have complained about the potential for terrorists to use the satellite images in planning attacks.[4] Google has blurred some areas for security (mostly in the United States),[5] including the U.S. Naval Observatory area (where the official residence of the Vice President is located), and previously[citation needed] the United States Capitol and the White House (which formerly featured this erased housetop). Other well-known government installations, including Area 51 in the Nevada desert, are visible.
Not all areas on satellite images are covered in the same resolution; less populated areas usually get less detail. Some areas may be obscured by patches of clouds.[6][7]

With the introduction of an easily pannable and searchable mapping and satellite imagery tool, Google's mapping engine prompted a surge of interest in satellite imagery. Sites were established which feature satellite images of interesting natural and man-made landmarks, including such novelties as "large type" writing visible in the imagery, as well as famous stadia and unique geological formations. As of November 2008[update], the U.S. National Weather Service also now uses Google Maps within its local weather forecasts, showing the 5 x 5 km "point forecast" squares used in forecast models.[8]

Although Google uses the word satellite, most of the high-resolution imagery is aerial photography taken from airplanes rather than from satellites.[9]

^ = not all roads are featured in this country, so directions are very limited.

* = has directions and places of interest.

Implementation

Like many other Google web applications, Google Maps uses JavaScript extensively. As the user drags the map, the grid squares are downloaded from the server and inserted into the page. When a user searches for a business, the results are downloaded in the background for insertion into the side panel and map; the page is not reloaded. Locations are drawn dynamically by positioning a red pin (composed of several partially-transparent PNGs) on top of the map images.

A hidden IFrame with form submission is used because it preserves browser history. The site also uses JSON for data transfer rather than XML, for performance reasons. These techniques both fall under the broad Ajax umbrella.

Extensibility and customization

As Google Maps is coded almost entirely in JavaScript and XML, some end users have reverse-engineered the tool and produced client-side scripts and server-side hooks which allowed a user or website to introduce expanded or customized features into the Google Maps interface.

Using the core engine and the map/satellite images hosted by Google, such tools can introduce custom location icons, location coordinates and metadata, and even custom map image sources into the Google Maps interface. The script-insertion tool Greasemonkey provides a large number of client-side scripts to customize Google Maps data.

Combinations with photo sharing websites, such as Flickr, are used to create "memory maps". Using copies of the Keyhole satellite photos, users have taken advantage of image annotation features to provide personal histories and information regarding particular points of the area.

Google Maps API

Google created the Google Maps API to allow developers to integrate Google Maps into their websites with their own data points. It is a free service, and currently does not contain ads, but Google states in their terms of use that they reserve the right to display ads in the future.[10]

By using the Google Maps API, it is possible to embed the full Google Maps site into an external website. Developers are required to request an API key,[11] which is bound to the website and directory entered when creating the key. The Google Maps API key is no longer required for API version 3. Creating a customized map interface requires adding the Google JavaScript code to a page, and then using Javascript functions to add points to the map.

When the API first launched, it lacked the ability to geocode addresses, requiring users to manually add points in (latitude, longitude) format. This feature has since been added for premier.

At the same time as the release of the Google Maps API, Yahoo! released its own Maps API.[12] The releases coincided with the O'Reilly Web 2.0 Conference. Yahoo! Maps, which lacks international support, included a geocoder in the first release.

As of October 2006[update], the implementation of Google Gadgets' Google Maps is simpler, requiring only one line of script, but it is not as customizable as the full API.

In 2006, Yahoo! began a campaign to upgrade its maps to compete better with Google and other online map companies. Several of the maps used in a survey were similar to Google maps.

Google Maps actively promotes the commercial use of its API. Some of its first large-scale adopters were real estate mash-up sites. Google performed a case study[13] about Nestoria, a property search engine in the UK and Spain.

Google Maps for Mobile

In 2006, Google introduced a Java application called Google Maps for Mobile, intended to run on any Java-based phone or mobile device. Many of the web-based site's features are provided in the application.[14]

On November 28, 2007, Google Maps for Mobile 2.0 was released. It introduced a GPS-like location service that does not require a GPS receiver. The "my location" feature works by utilizing the GPS location of the mobile device, if it is available. This information is supplemented by the software determining the nearest wireless networks and cell sites. The software then looks up the location of the cell site using a database of known wireless networks and cell sites. The Cell-site location method is used by triangulating the different signal strengths from different cell transmiters and then using their location property (retrieved from the online cell site database) to aid My Location in determining the user's current location. Wireless network location method is calculated by discovering the nearby WiFi hotspots and using their location property (retrieved from the online WiFi database, in the same way as the cell site database) to further discover the user's location.
The order in which these take precedence is:

GPS-based services

WLAN-based / WiFi-based services

Cell transmitter-based services

The software plots the streets in blue that are available with a yellow icon and a green circle around the estimated range of the cell site based on the transmitter's rated power (among other variables). The estimate is refined using the strength of the cell phone signal to estimate how close to the cell site the mobile device is.

As of December 15, 2008 (2008 -12-15)[update], this service is available for the following platforms:[15]

On November 4, 2009, Google Maps Navigation was released in conjunction with Google Android OS 2.0 Eclair on the Motorola Droid, adding voice commands, traffic reports, and street view support.[16] The initial release is limited to the United States.[17]

Google Maps Android 2.0.
Cell phones are being increasingly used for navigation assistance. However, written driving instructions are sometimes very confusing to follow. While navigation devices have become a billion dollar industry, Google Maps Navigation for Android 2.0 is free. An iPhone implementation is also being planned.[18]

Impact
Google Maps Navigation is free and this will have a major impact on the navigation industry. The drawback of Google Maps for Android is that an internet connection is required to get maps and related information from Google Maps, just like with iPhone’s Google Maps application. It may be possible for Google to circumvent the Internet requirement. A similar system is being developed for the iPhone.[19]

Shares of Tom-Tom, Garmin and other navigation service providers fell by almost twenty-five percent (25%) after Google's announcement of Google Maps for Navigation. The application is only available initially to Verizon users with Android 2.0 or higher. It is doubtful that users will continue to pay for navigation service if Google provides it for free.

Google Map Navigation is interrupted in cell phone dead zones. In contrast, iPhone’s app operates as a traditional GPS device when there’s no cell phone signal. This is particularly relevant on streets with high rise buildings and on highways.[20]

Google Maps parameters

In Google Maps, URL parameters may be tweaked to offer views and options not normally available through on-screen controls.

For instance, the maximum zoom level offered is normally 18, but if higher-resolution images are available, changing the z parameter, which sets the zoom level, will allow the user to access them, as in
this view of elephants or this view of people at a well deep in Chad, Africa using the parameter z=23.

Development history

Google Maps first started as a software application developed by Lars and Jens Rasmussen for the company Where2. In October 2004 the company was acquired by Google Inc[21] where it transformed into the web application Google Maps. The application was first announced on the Google Blog on February 8, 2005,[22] and was located at Google.[23] It originally only supported users of Internet Explorer and Mozillaweb browsers, but support for Opera and Safari was added on February 25, 2005, but currently Opera is removed from the system requirements list. Currently (September 2009) Internet Explorer 6.0+, Firefox 2.0+, Safari 3.1+, and Google Chrome are supported.[24] It was in beta for six months before becoming part of Google Local on October 6, 2005.

In September 2005, in the aftermath of Hurricane Katrina, Google Maps quickly updated its satellite imagery of New Orleans to allow users to view the extent of the flooding in various parts of that city. (Oddly, in March 2007, imagery showing hurricane damage was replaced with images from before the storm; this replacement was not made on Google Earth, which still uses post-Katrina imagery).[25][26]

As of January 2, 2006 (2006 -01-02)[update], Google Maps featured road maps for the United States, Puerto Rico, Canada, the United Kingdom, Japan, and certain cities in the Republic of Ireland. Coverage of the area around Turin was added in time for the 2006 Winter Olympics.

On January 23, 2006, Google Maps was updated to use the same satellite image database as Google Earth.

On November 27, 2007, "Terrain" view showing basic topographic features was added. The button for "Hybrid" view was removed, and replaced with a "Show labels" checkbox under the "Satellite" button to switch between "Hybrid" and "Satellite" views.

In October 2009, the railroads were redone, featuring a slightly new look and updated, removing older lines.[citation needed] Also in the same month, maps in several areas were changed to include paper streets and other odd roads that don't exist, as well as lot lines showing up on the map interface.[citation needed]

Google's use of Google Maps

The main Google Maps site includes a local search feature, which can be used to locate businesses of a certain type in a geographic area.

Google Ditu

Google Ditu (谷歌地图 lit. "Google Maps") was released to the public on February 9, 2007, and replaced the old Google Bendi (谷歌本地 lit. "Google Local"). This is the Chinese localized version of Google Maps and Google Local services.

Google Moon

In honor of the 36th anniversary of the Apollo 11 moon landing on July 20, 1969, Google took public domain imagery of the Moon, integrated it into the Google Maps interface, and created a tool called Google Moon.[36] By default this tool, with a reduced set of features, also displays the points of landing of all Apollo spacecraft to land on the Moon. It also included an easter egg, displaying a Swiss cheese design at the highest zoom level, which Google has since removed. A recent collaborative project between NASA Ames Research Center and Google is integrating and improving the data that is used for Google Moon. This is the Planetary Content[37] Project. Google Moon was linked from a special commemorative version of the Google logo displayed at the top of the main Google search page for July 20, 2005 (UTC) webarchive.org.

Now, with Google Earth 5 it is possible to access new improved Google Mars data at a much higher resolution, as well as being able to view the terrain in 3D, and viewing panoramas from various Mars landers in a similar way to Google Street View.

Google Ride Finder

Google launched an experimental Google Maps-based tool called Ride Finder, tapping into in-car GPS units for a selection of participating taxi and limousine services. The tool displays the current location of all supported vehicles of the participating services in major U.S. cities, including Chicago and San Francisco on a Google Maps street map. As of 2009 the tool seems to be discontinued. Not to be confused with carpooling.

Google Transit

In December 2005, Google launched Google Transit on Google Labs a 20% project of Chris Harrelson and Avichal Garg.[39] Google Transit launched initially with support for Portland, Oregon, and now includes hundreds of cities in the United States, Canada, Europe, Asia, Africa, and Australia. The service calculates route, transit time and cost, and can compare the trip to one using a car. In October 2007,[40] Google Transit graduated from Google Labs and became fully integrated into Google Maps.

Google My Maps

In April 2007, My Maps was a new feature added to Google's local search maps. My Maps lets users and businesses create their own map by positioning markers, polylines and polygons onto a map. The interface is a straightforward overlay on the map. A set of eighty-four pre-designed markers is available, ranging from bars and restaurants to webcam and earthquake symbols. Polyline and Polygon color, width and opacity are selectable. Maps modified using My Maps can be saved for later viewing and made public or marked as private.

Each element added to a My Map has an editable tag. This tag can contain text, rich text or HTML. Embeddable video and other content can be included within the HTML tag.

Upon the launch of My Maps there was no facility to embed the created maps into a webpage or blog. A few independent websites have now produced tools to let users embed maps and add further functionality to their maps.[41] This has been resolved with version 2.78.

Google Street View

On May 25, 2007, Google released Street View, a new feature of Google Maps which provides 360° panoramic street-level views of various U.S. cities. On this date, the feature only included five cities, but has since expanded to thousands of locations in the United States, United Kingdom, Netherlands, France, Italy, Spain, Switzerland, Australia, Canada, New Zealand, Japan and the Czech Republic.

In August 2008, Australia was added to the Street View feature with nearly all Australian highways, roads and streets having the feature. In addition in that month Japan was added and the Tour de France route was added on July 2 of that year.
In December 2008, New Zealand was added to street view. Australia and New Zealand are the only countries to date with almost all roads and highways featured.

July 2009, Google begins mapping college campuses and surrounding paths and trails.[42]

Google Street View gained a significant amount of controversy in the days following its release. Initially privacy concerns erupted due to the uncensored nature of its panoramic photographs.[43][44] Since then, Google has begun blurring faces using an automated face detection technology.[45]

Google Latitude

Google Latitude is a feature from Google that lets users share their physical locations with other people. This service is based on Google Maps, specifically on mobile devices. There's an iGoogle widget for Desktops and Laptops as well.[46] Some concerns have been expressed about the privacy issues raised by the use of the service.[47]

Monopoly City Streets

Mashups

Google maps links to the geo-tags placed in Wikipedia articles. It also links to photos with GPS tags from Panoramio.

Copyright

The Google Maps terms and conditions[49] state that usage of material from Google Maps is regulated by Google Terms of Service[50] and some additional restrictions. The terms and conditions also state:

For individual users, Google Maps [...] is made available for your personal, non-commercial use only. For business users, Google Maps is made available for your internal use only and may not be commercially redistributed [...][49]

Criticism

Street map overlays, in some areas, may not match up precisely with the corresponding satellite images. The street data may be entirely erroneous, or simply out of date:

The biggest challenge is the currency of data, the authenticity of data," said Google Earth representative Brian McLendon. In other words: The main complaints the Google guys get are "that's not my house" and "that's not my car." Google Maps satellite images are not in real time; they are several years old.[51]

As a result, in March 2008 Google added a feature to edit the locations of houses and businesses.[52][53]

Restrictions have been placed on Google Maps through the apparent censoring of locations deemed potential security threats. In some cases the area of redaction is for specific buildings, but in other cases, such as Washington, D.C.,[54] the restriction is to use outdated imagery. These locations are fully listed on Satellite map images with missing or unclear data.

Google Maps has difficulty processing road data when dealing with cross-boundary situations. For example, users are unable to obtain a route from Hong Kong to Shenzhen via Shatoujiao, because Google Maps does not display and plan the road map of two overlapping places.[55]

Sometimes objects on Google Maps are hidden by clouds. For example, the mast of Arbrå Transmitter near Bollnäs in Sweden is hidden under a cloud.

The map uses the Mercator projection, which is increasingly distorted towards the polar regions.

Sometimes the names of geographical locations are inaccurate. An example of this type of error may be found in Google Maps Laona, Wisconsin. In this instance Google Maps identifies one of the town's two major lakes as "Dawson Lake";[56] the USGS, State of Wisconsin, and local government maps all identify that map feature as "Scattered Rice Lake".[57] Another example is Samoa, labeled with "Western Samoa", accurate only as recently as 1997.

Google collates business listings from multiple on-line and off-line sources. To reduce duplication in the index, Google's algorithm combines listings automatically based on address, phone number, or geocode,[58] but sometimes information for separate businesses will be inadvertently merged with each other, resulting in listings inaccurately incorporating elements from multiple businesses.[59]

Google has also recruited volunteers to check and correct ground truth data.[60]

There are some differences in frontier alignments between Google Ditu and Google Maps. On Google Maps, sections of the Chinese border with India and Pakistan are shown with dotted lines, indicating areas or frontiers in dispute. However, Google Ditu shows the Chinese frontier strictly according to Chinese claims with no dotted lines indicating the border with India and Pakistan. For example, the area now administered by India called Arunachal Pradesh (referred to as "South Tibet" by China) is shown inside the Chinese frontier by Google Ditu, with Indian highways ending abruptly at the Chinese claim line. Google Ditu also shows Taiwan and the South China Sea Islands as part of China. As of May 2009, Google Ditu's street map coverage of Taiwan also omits major state organs, such as the Presidential Palace, the five Yuans, and the Supreme Court.

There are some differences between ditu.google.cn and ditu.google.com. For example, the former does not feature My Maps. On the other hand, while the former displays virtually all text in Chinese, the latter displays most text (user-selectable real text as well as those on map) in English. This behavior of displaying English text is not consistent but intermittent - sometimes it is in English, sometimes it is in Chinese. The criteria for choosing which language is displayed is not known.